Cylinder compressions low on an IO-360

Salty said:
At the risk of causing further damage and increasing cost, or having to pull the cylinder anyway meaning paying for the “don’t pull it repair” in addition to the real repair.
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cost over the life of the cylinder. ?

one 0-300 operator has well over 2000 hours on his cylinders by cleaning the valve and honing the guides every 100 hours. most of the 0-300 operators are replacing their cylinders at 12-1400 hours.

do the math, 0-300 cylinders are over $1000.00 each
 
Salty said:
That’s the point. You don’t actually know what’s wrong.
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knowing the symptoms, you can tell, it isn't that difficult to know when the air is blowing into the crank case, the piston assembly is at fault. or when the air is coming out the exhaust it is the exhaust valve at fault.
A&Ps are pretty savvy about this.

and why don't you believe that cleaning the valve stem, and honing the guide isn't a real repair when that alone will restore the compression to acceptable levels?
 
Tom-D said:
one 0-300 operator has well over 2000 hours on his cylinders by cleaning the valve and honing the guides every 100 hours. most of the 0-300 operators are replacing their cylinders at 12-1400 hours.
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Every 100 hours? What happened to fix it right a few posts back? :rolleyes: If a circuit breaker keeps tripping, do you just keep resetting it over and over and over?

If this really is the case, his labour must be really low and his tolerance for making due must be really high.
 
JAWS said:
Every 100 hours? What happened to fix it right a few posts back? :rolleyes: If a circuit breaker keeps tripping, do you just keep resetting it over and over and over?

If this really is the case, his labour must be really low and his tolerance for making due must be really high.
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Do you really relate a cylinder to a circuit breaker?
 
JAWS said:
Every 100 hours? What happened to fix it right a few posts back? :rolleyes: If a circuit breaker keeps tripping, do you just keep resetting it over and over and over?

If this really is the case, his labour must be really low and his tolerance for making due must be really high.
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If you weren't constrained by the regs, you maybe could "Fix it right" but it's a locked in what, 70 or 80 year old design? If you do it as part of your annual, since low hours are typical and low hours probably exacerbate the problem, it becomes scheduled maintenance. What's the alternative would you remove the jug to accomplish the exact same thing, or are you voting for a complete new replacement because of a sticky valve stem? Not trying to be a jerk, just curious.
 
Lantraxco said:
If you weren't constrained by the regs, you maybe could "Fix it right" but it's a locked in what, 70 or 80 year old design? If you do it as part of your annual, since low hours are typical and low hours probably exacerbate the problem, it becomes scheduled maintenance. What's the alternative would you remove the jug to accomplish the exact same thing, or are you voting for a complete new replacement because of a sticky valve stem? Not trying to be a jerk, just curious.
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I would be looking for an answer why a fairly evasive procedure has to be done over and over to keep an engine airworthy. I have worked on these old designs and I have never seen or advocated going to the well so often. If a circuit breaker pops, do you just keep resetting it? If a tire loses pressure over and over, do you just keep refilling it instead of maybe looking deeper into why?

Just doesn't seem right to me.
 
JAWS said:
I would be looking for an answer why a fairly evasive procedure has to be done over and over to keep an engine airworthy. I have worked on these old designs and I have never seen or advocated going to the well so often. If a circuit breaker pops, do you just keep resetting it? If a tire loses pressure over and over, do you just keep refilling it instead of maybe looking deeper into why?

Just doesn't seem right to me.
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I think you're missing the point, you check spark pugs at annual and clean or replace them, it's scheduled/preventive maintenance.

"one 0-300 operator has well over 2000 hours on his cylinders by cleaning the valve and honing the guides every 100 hours. most of the 0-300 operators are replacing their cylinders at 12-1400 hours."

Sounds like the procedure is keeping your circuit breaker from ever tripping.... maybe 200 hours or 300 hours would work fine, research would be required.....

So cleaning valve stems and guides is just preventive maintenance for a problem that probably radically shortens the useful life of the cylinders. Again, what's the fix, if the problem is typical and most owners either are unaware or choose to ignore it until the engine needs major repair? I think the problem is obvious, the permanent solution perhaps not so much?
 
Maybe the guides are shot at 1400 hrs and repeated cleaning is squeaking them along to the 2000 hour mark. Doesn't seem very wise to me.

But it isn't my plane and the owner can do what he likes.

Lantraxco said:
I think the problem is obvious, the permanent solution perhaps not so much?
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Tom-D said:
Why should they be when they are cared for properly?
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Different strokes for different folks, I guess.

arnoha said:
Fortunately for me, it was caught during 100-hour, at the home airport, in the club MX hangar, so there's no need for jury-rigged tricks on this cylinder failure.
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Awesome! :)
 
Tom-D said:
Can't answer the question?
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Some people believe using sealant on cylinders is normal. Some don't. Some people believe reaming valve guides every 100 hours is normal. Some don't.

Different strokes for different folks.
 
JAWS said:
I would be looking for an answer why a fairly evasive procedure has to be done over and over to keep an engine airworthy.
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Likely because many pilots don't run their engine LOP, which contributes to carbon build up.
 
Ray Eaker said:
Likely because many pilots don't run their engine LOP, which contributes to carbon build up.
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Like pretty much everyone with a carburetor?
 
arnoha said:
No engine monitor. Still has only the stock engine equipment...single point EGT, oil temp, oil pressure, fuel flow (that's really fuel pressure). No CHT, no per-cylinder EGT, no flow transducer. I've debated putting a monitor in. Everyone I've spoken to says it's pricey overkill for a 172 and that it'll just confuse the students. I'm beginning to think that may be bad advice.
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Definitely bad advice. The monitor isn't for them - It's for you. You can download the data (do not even bother with one that doesn't log data!) and you can figure out a LOT of things: Whether anyone is abusing the engine, whether something is normal or not and when it changed, and you can save a ton of money on troubleshooting.

Example: Plane goes out for a flight, but runs rough on runup.
No engine monitor: "Hey Mr. A&P, this engine is running rough on the mag check."
Engine monitor: "Hey Mr. A&P, I need you to replace the bottom spark plug on the #4 cylinder."

Which do you think is going to cost you less?

Another example, from when I was the club's maintenance officer: I got a squawk that the #4 cylinder on the DA40 was running hot. If I hadn't had any engine data, I'd have needed to call the shop and tell them that. They would have looked at the baffling, maybe adjusted things, maybe done some other checks on the engine looking for the problem, but it wouldn't have fixed anything (see below) and we would have spent a lot of money to troubleshoot it with no fix, meaning it probably would have gone into the shop more than once.

But, because I had engine data (and lots of other data from the G1000), I was able to look back through 5 years of operation and find that that cylinder was running the same as it always had under similar conditions (OAT, altitude, airspeed, power setting). I was even able to get data from another plane that was one serial number away from ours from cirrusreports.com and find that it, too, ran hotter on #4 than the rest and had similar temps for similar conditions, and so did some other DA40s. So, it was perfectly normal and we spent exactly $0 paying an A&P to go searching for a nonexistent problem.

asicer said:
Can't speak to the first part, but as for the second part the G1000 has a built-in monitor/analyzer and primary students don't seem to be too confused by it.
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At least, no more confused than they are with the rest of the G1000. ;)
 
Salty said:
Like pretty much everyone with a carburetor?
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Nah. Everyone without an engine monitor for all cylinders... yeah. Some carb'd engines are known to not like LOP but many Lycomings are fine with it - though not to the extent of a FI engine with balanced injectors.
 
flyingcheesehead said:
Example: Plane goes out for a flight, but runs rough on runup.
No engine monitor: "Hey Mr. A&P, this engine is running rough on the mag check."
Engine monitor: "Hey Mr. A&P, I need you to replace the bottom spark plug on the #4 cylinder."

Which do you think is going to cost you less?
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Neither,,,, the smart A&P will trouble shoot to their own satisfaction. and charge accordingly.
 
6 AMU is what the damn 100-hour ended up costing. 4 of that was the two cylinders, which were replaced. Still don't know what caused the issue. (The rest...$1500 for the inspection and $500 in random snags...air filter, cowl fastener, nose strut fill, door stop. And a major clean and degrease inside and out.)

The month of January had no income, so I'm really not looking forward to this month's statement.
 
arnoha said:
More bad news...I was just informed that, during a 100-hour, the IO-360-L2A in my 172S read 20/80 on cylinders 1 and 2. The kicker? Cylinder #1 was replaced in February, about 300 hours ago, due to reading nearly no compression. #2 is likely from the overhaul, 1200 hours ago. The shop is evaluating right now, but I'm curious what could be causing repeated failures like this? What sorts of questions should I be asking? This is very frustrating...the parallel valve IO-360 is supposed to be bulletproof.

EDIT: Another thing I should note, since this plane is a leaseback, it gets 100 hour inspections. At the last 100 hour, compressions were fine. Need to go figure out exactly how high, but it was high enough that no concern at all was noted, so I'm assuming over 65/80. Whatever happened, it didn't give any warning. Oil analysis was also clean.
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Read the book - Mike Busch On Engines. It was an eye opener for me as a non mechanic, tinkerer type. Better yet, write Mike himself. I was surprised when he wrote me back with an answer to a question. His email is
mike.busch at savvyaviation.com. He gives his email out freely in his many youtube presentations, so I don't feel guilty passing it along. Good luck with your problem.
 
Eric D Klee said:
Read the book - Mike Busch On Engines. It was an eye opener for me as a non mechanic, tinkerer type. Better yet, write Mike himself. I was surprised when he wrote me back with an answer to a question. His email is
mike.busch at savvyaviation.com. He gives his email out freely in his many youtube presentations, so I don't feel guilty passing it along. Good luck with your problem.
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Thanks. I own the book. Unfortunately, my hands are often tied on these issues. The insurance company won't insure the plane with the low cylinders, so if the plane is to fly, I must replace. :(
 
arnoha said:
The insurance company won't insure the plane with the low cylinders,
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I've never heard of this being a condition to insure.
Unless the aircraft is declared un-airworthy.
 
arnoha said:
Thanks. I own the book. Unfortunately, my hands are often tied on these issues. The insurance company won't insure the plane with the low cylinders, so if the plane is to fly, I must replace. :(
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Hmmm. This sounds fishy. Is this your insurance, or the FBO's? And are they the ones doing the maintenance?

I've just heard this "insurance won't cover x" crap too many times, and usually it's the FBO's excuse for a poorly-conceived rule. I'm betting the FBO has it on their insurance and you're using their shop, right? Because if that's the case, I would demand to see the policy. Like Tom, I've never heard of an actual policy like that before...
 
several years ago i heard that wvfc insurance policy has almost no limitations on the who/what is flying (at least in the hours minimums and check out requirements) and their insurance provider relies on the club to self-manage the risk and keep the premiums low. and this is what they are doing - self managing the risk. things could have changed since then though
 
flyingcheesehead said:
Hmmm. This sounds fishy. Is this your insurance, or the FBO's? And are they the ones doing the maintenance?

I've just heard this "insurance won't cover x" crap too many times, and usually it's the FBO's excuse for a poorly-conceived rule. I'm betting the FBO has it on their insurance and you're using their shop, right? Because if that's the case, I would demand to see the policy. Like Tom, I've never heard of an actual policy like that before...
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When he says he owns “the book” I am assuming he means he is the insurance agent also
 
Tom-D said:
cost over the life of the cylinder. ?

one 0-300 operator has well over 2000 hours on his cylinders by cleaning the valve and honing the guides every 100 hours. most of the 0-300 operators are replacing their cylinders at 12-1400 hours.

do the math, 0-300 cylinders are over $1000.00 each
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How does one ream a valve guide and not increase ID each time?
 
Isosceles said:
several years ago i heard that wvfc insurance policy has almost no limitations on the who/what is flying (at least in the hours minimums and check out requirements) and their insurance provider relies on the club to self-manage the risk and keep the premiums low. and this is what they are doing - self managing the risk. things could have changed since then though
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There's definitely some of that going on. I'll ask Steve about it. I do know that the insurance rates at WVFC are the lowest commercial rates I've ever seen. I guess I put up with it a bit as it knocks about $200 off the insurance bill every month. $2400 each year pays for a cylinder. (Of course, I've had to replace three, so...things to think about.)
 
1RTK1 said:
When he says he owns “the book” I am assuming he means he is the insurance agent also
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I'm assuming he means the Mike Busch engine book that was being talked about in the post that he quoted. ;)
 
flyingcheesehead said:
Hmmm. This sounds fishy. Is this your insurance, or the FBO's? And are they the ones doing the maintenance?

I've just heard this "insurance won't cover x" crap too many times, and usually it's the FBO's excuse for a poorly-conceived rule. I'm betting the FBO has it on their insurance and you're using their shop, right? Because if that's the case, I would demand to see the policy. Like Tom, I've never heard of an actual policy like that before...
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This is commercial insurance arranged through the flying club that manages my plane. They are not an FBO, but rather a flying non-profit. (West Valley Flying Club in Palo Alto, my plane there: http://www.wvfc.org/a/wvfc.org/template-2/aircraft/n194sp ) They do have some of the most draconian rules that I've seen about stuff like this. They also have a stellar safety record, excellent insurance, and cheap rates. They also run their own shop and run their own fuel service. (So...what makes it not an FBO, you ask? The answer: you must be a club member to use any of these services, except for the fuel.) They're popular, too, with over 50 aircraft that tend to stay very busy.

Palo Alto is a weird airport. Very small towered airport. Three major clubs, and a few smaller ones. Over 150 total aircraft available for rent...and they definitely get rented and fly, mine included. I'm typically getting 40-60 hours each month when the plane is healthy.
 
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